Method and apparatus for galvanizing steel strip on one side



Jan. 11, 1966 TEPLlTZ 3,228,788

METHOD AND APPARATUS FOR GALVANIZING STEEL STRIP ON ONE SIDE Filed May 4, 1962 Ar/arney United States Patent 3,228,788 METHOD AND APPARATUS FOR GALVANIZING STEEL STRIP 0N ONE SIDE Alfred Teplitz, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Filed May 4, 1962, Ser. No. 192,387 1 Claim. (Cl. 117-111) This invention relates to the manufacture of sheet steel galvanized on one side only and particularly to an improved method and apparatus for making such product continuously.

For certain industrial uses, sheet steel galvanized on one side but bare on the other is desirable. Green et al. Patent #2,894,850 discloses one method of making the product but that method has some disadvantages. It is accordingly the object of my invention to provide a simple, inexpensive and efiicient process which is readily adaptable to present galvanizing lines.

In a preferred embodiment and practice of my invention, I journal a coating roll horizontally above a spelter bath so that the lower portion of the roll is immersed in the bath. I pass steel strip over the roll and in contact with the top portion of its periphery. The roll turns in the spelter, picks up a film thereof and applies it to the lower surface of the strip. The surface of the spelter and the coating roll are preferably enclosed in a muffle and a shielding or gaging roll is journaled closely adjacent the coating roll, approximately at the level of the surface of the bath.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings, the single figure is a central vertical section through a galvanizing pot having mounted thereon the apparatus for carrying out my improved method.

Referring now in detatil to the drawing, a galvanizing pot is provided with any conventional heating means (not shown) and is filled with molten spelter up to a level 11, slightly below the upper edges of the pot walk. A coating roll 12 is journaled horizontally near the level 11, conveniently in bearings( not shown) secured to the pot walls. As shown, the lower portion only of the roll is immersed in the spelter. Deflector rolls 13 and 14 are similarly journaled, one on each side of and above roll 12 so as to guide strip S strained around them into contact with the upper portion of roll 12.

A shielding, pumping and gaging roll 15 is journaled similarly adjacent the top of the bath as shown and is preferably adjustable toward and from roll 12. Roll 15 prevents dross floating on the bath from approaching the ascending side of roll 12, aids the latter by a pumping action to pick up a spelter film, and may also serve to determine the thickness of the film picked up.

A muffle 16 encloses the space above the bath surface 12 and, at its entrance end 17, it communicates with a strip annealing furnace. The special atmosphere in the furnace therefore fills the mufile and continues to protect the strip S while passing therethrough. The exit end 18 of the mufile is provided with sealing rolls 19 between which the strip passes. Between roll 14 and rolls 19 are positioned smoothing rolls 20 adapted to engage the galvanized side of strip S while the coating is still molten, to spread it uniformly over the strip surface. Rolls 20 are journaled in bearings (not shown) suitably supported on the pot 10 or muflie 16.

Low-carbon steel strip S entering the inlet end of the muffle passes around deflector roll 13, over coating roll 3,228,788 Patented Jan. 11, 1966 12, then around deflector roll 14 and past smoothing rolls 20 before passing out of the muflie between sealing rolls 19. As already indicated, the roll 12 picks up a film of molten zinc from the surface of the bath and applies it to the lower surface of strip S. The coating thus applied is still soft enough to be spread and smoothed uniformly by rolls 20 as the strip comes in contact therewith but is solidified before the strip enters the sealing rolls. Artificial cooling may be applied in any convenient manner, if necessary, to achieve such solidification.

Roll 12 may be driven, if desired, at a peripheral speed equal to or greater than that of the strip. The strip is drawn through the annealing furnace and the galvanizing apparatus by conventional traction means not shown. Rolls 12 and 15 may have special surfaces, i.e., grooved or knurled, if needed, to aid them in picking up a film of spelter from bath 11. Roll 14 should have a length less than the width of strip S so it will not pick up spelter which may creep around the strip edges by capillary attraction.

After the strip emerges from the exit end 19 of the muffle 16 it may be cooled by contact with the atmosphere or otherwise and is then finished and sheared into sheets or coiled, in the known manner.

It will be recognized that my invention is characterized by important advantages. It is readily adaptable to existing continuous strip-galvanizing lines and requires but little change in present installations. It does not involve any change in established annealing practice or other precoating treatment. The cost of the operation is no more than that of coating on both sides and the material cost is reduced about half.

Although I have disclosed herein the preferred embodiment and practice of my invention, I intend to cover as Well any change or modification therein which may be made without departing from the spirit and scope of the invention.

I claim:

A method of galvanizing a sheet steel base on one side only comprising providing a bath of molten zinc having dross therein, causing a rotating horizontal roll to dip below the surface of the bath to pick up a zinc film therefrom over the full width thereof, providing a second rotating roll of substantially the same length as the first roll with a portion thereof below the surface of the bath, positioning the second roll with its axis substantially parallel to the axis of the first roll and its outer surface spaced a short distance from the outer surface of the first roll at the line of approximate tangency to gage the film on the second roll and prevent dross from approaching the ascending side of the first roll, and bringing a sheet-steel base over said first mentioned roll in contact with an arc of the circumference thereof, whereby said film is transferred to said base.

References Cited by the Examiner UNITED STATES PATENTS 1,928,160 9/1933 Watkins et al. 118-22 2,462,474 2/1949 Delano 118-118 2,483,652 10/1949 Lee 118-118 2,556,262 6/1951 Faeber 117-111 2,611,717 9/1952 Sooy et al 117-111 2,937,108 5/1960 Toye 117-51 2,968,091 1/1961 Schoenfeld 117-111 X 3,086,879 4/1963 La-ssifer 117-111 X RICHARD D. NEVIUS, Primary Examiner.

WILLIAM D. MARTIN, Examiner. 

